Non-dripping nozzle apparatus

ABSTRACT

According to one aspect of the invention, a dispense head for a wafer processing apparatus is provided. The dispense head may include an inlet, at least one outlet, a drain, and a passageway therethrough interconnecting the inlet, the outlet, and the drain. The inlet may be at a first height above a bottom of the passageway, the outlet may be a second height above the bottom of the passageway, and the drain may be a third height above the bottom of the passageway. A first valve may be connected to the inlet, and a second valve may be connected to the drain. When the first valve is opened and the second valve is closed, fluid flows into the inlet and out of the outlet. When the second valve is opened and the first valve is closed, fluid from the passageway flows out of the drain. A pump may be connected to the drain.

This is a Divisional Application of Ser. No. 10/743,928 filed Dec. 22,2003, which is presently pending.

BACKGROUND OF THE INVENTION

1). Field of the Invention

This invention relates to a semiconductor substrate processing apparatusand a method of processing a semiconductor substrate.

2). Discussion of Related Art

Integrated circuits are formed on semiconductor wafers. The formation ofthe integrated circuits may include numerous processing steps such asdeposition of various layers, etching some of the layers, and multiplebakes.

Often the processing of semiconductor wafers takes place in large waferprocessing machines. One of the components found in these machines areknown as modules. These modules may receive a semiconductor wafer from aanother component, place the wafer on a wafer support, and dispense asolution or solvent onto the wafer as one of the many steps included inwafer processing. The solution may be dispensed onto the wafers from adispense head that is moved into a position over the wafer. Typically,the solution is fed into inlets of the dispense head through a valve anddispensed onto the wafer through nozzles on the dispense head.

After the solution is dispensed, unwanted solution often leaks or dripsonto the wafer or another part of the module due to vibrations of thedispense head as it is moved, extra solution remaining in the dispensehead, and air rising through the nozzles on the dispense head. Thisunwanted solution can damage the integrated circuits that are beingformed and lead to increase maintenance costs of the wafer processingmachine. One solution is to use a “suck-back” valve on the dispensehead, which creates a vacuum back though the inlet causing excesssolution to be drawn back through the inlet. However, the suck-backvalves are expensive and are not completely effective as some solutionstill leaks from the dispense head.

SUMMARY OF THE INVENTION

The invention provides a dispense head for a semiconductor substrate, orwafer, processing apparatus. The dispense head may include an inlet, atleast one outlet, a drain, and a passageway therethrough interconnectingthe inlet, the outlet, and the drain. The inlet may be a first heightabove a bottom of the passageway, the outlet may be a second heightabove the bottom, and the drain may be a third height above the bottom.A first valve may be connected to the inlet, and a second valve may beconnected to the drain. When the first valve is opened and the secondvalve is closed, fluid flows into the inlet and out of the outlet. Whenthe second valve is opened and the first valve is closed, fluid from thepassageway flows out of the drain. A pump may be connected to the drain.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described by way of example with reference to theaccompanying drawings, wherein:

FIG. 1 is a cross-sectional side view of a module stack in asemiconductor wafer processing system, including developer modules and acomputer controller;

FIG. 2 is a perspective view of one of the developer modules of FIG. 1,including a dispense arm;

FIG. 3 is a bottom perspective view of the dispense arm, including adispense head; and

FIGS. 4 a-4 f are cross-sectional schematic views of the dispense headsuspended over a semiconductor wafer.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 to FIG. 4 f of the accompanying drawings illustrate a dispensehead for a semiconductor substrate, or wafer, processing apparatus. Thedispense head may include an inlet, at least one outlet, a drain, and apassageway therethrough interconnecting the inlet, the outlet, and thedrain. The inlet may be a first height above a bottom of the passageway,the outlet may be a second height above the bottom, and the drain may bea third height above the bottom. A first valve may be connected to theinlet, and a second valve may be connected to the drain. When the firstvalve is opened and the second valve is closed, fluid flows into theinlet and out of the outlet. When the second valve is opened and thefirst valve is closed, fluid from the passageway flows out of the drain.A pump may be connected to the drain.

FIG. 1 illustrates a module stack 10 from a semiconductor waferprocessing system. In an embodiment, the module stack 10 may include aframe 12, developer modules 14, and a computer controller 16. Thedeveloper modules 14 may be vertically stacked and may be substantiallyidentical. The computer controller 16 may lie on top of the developermodules 14 and although not shown in detail, may be electricallyconnected to the developer modules 14, and include a computer with amemory for storing a set of instructions and a processor connected tothe memory for executing the instructions, as is commonly understood inthe art.

FIG. 2 illustrates one of the developer modules 14. The developer module14 may include a base 18, a wafer chuck 20, a catch cup 22, and adispense arm 24.

The base 18 may be attached to the frame 12 of the module stack 10 andbe substantially cubic in shape. The wafer chuck 20, or wafer support,may be on top of the base 18, circular in shape, and connected to thebase 18 to rotate about a central axis thereof. The wafer chuck 20 mayhave an upper surface, which although not shown in detail, issubstantially flat and in a plane to support a semiconductor wafer.Although not shown, it should be understood that the base 18 may includean electric motor, or other actuator, to rotate the wafer chuck 20 aboutthe central axis thereof, along with a semiconductor wafer supported bythe wafer chuck 20. The catch cup 22 may substantially be an annular,ring-shaped body attached to the top of the base 18, which taperstowards the central axis of the wafer chuck 20 the further the catch cup22 extends from the base 18.

FIG. 3 illustrates the dispense arm 24. The dispense arm 24 may includea vertical piece 26, a horizontal piece 28, and a dispense head 30. Asillustrated in FIGS. 2 and 3, the vertical piece 26 may be verticallyattached to the base 18, and the horizontal piece 28 may be attached tothe vertical piece 26 at a first end thereof so that it may translatetransverse to the plane of the wafer chuck 20 and rotate over the waferchuck 20. The dispense head 30 may be attached to a second end of thehorizontal piece 28.

As illustrated in FIG. 3, the vertical piece 26 may include a rotationalactuator 32 and a vertical actuator 34. The rotational actuator 32 maybe an electric motor, or other such suitable actuator, which isconnected to the dispense arm 24 to rotate the horizontal piece 28 andthe dispense head 30 back and forth over the wafer chuck 20. Thevertical actuator 34 may be a pneumatic actuator, or other such suitableactuator, which is connected to the base 18 and the horizontal piece 28to translate the horizontal piece 28 transverse to the plane of thewafer chuck 20.

FIGS. 4 a-4 f illustrate the dispense head 30 suspended over the waferchuck 20. The dispense head 30 may include a bottom piece 36, a sidewall38, a top piece 40, and a channel 42 therein. Although only shown incross-section, it should be understood, as illustrated in FIG. 3, thatthe dispense head 30 and all its components may have a substantiallyrectangular shape and may have a dimension, such as length, that maycorrespond to a radius of a semiconductor wafer. The dispense head 30may further include a plurality of nozzles 44.

The bottom piece 36 may have a substantially flat upper surface 46 andinclude a plurality of nozzle openings 48 therethrough. The uppersurface 46 of the bottom piece 36 may form a bottom of the channel 42.Each of the nozzles 44 may be held within a respective nozzle opening 48and may have an outlet opening 50 at an upper end thereof. The outletopenings 50 may be at an outlet height 52 above the upper surface 46 ofthe bottom piece 36. The nozzles 44 may have a diameter 54, for example,of between 0.02 and 0.04 inch.

The sidewall 38 may be attached to a periphery of the bottom piece 36and extend upwards therefrom. A portion of the sidewall 38 may have adrain opening 56 therethrough. The drain opening 56 may be adjacent tothe upper surface 46 of the bottom piece 36. The drain opening 56 mayhave a drain height 58, which may be less than the outlet height 52above the upper surface 46 of the bottom piece 36. In the embodimentshown, because the drain opening 56 is adjacent to the upper surface 46of the bottom piece 36, the drain height 58 corresponds to a diameter ofthe drain opening 56. It should be understood the drain opening 58 doesnot have to be adjacent to the upper surface 46 of the bottom piece. Thedrain height 58, or the diameter of the drain opening 56, may be, forexample, at least between 0.10 and 0.20 inch.

The top piece 40 may be attached to an upper end of the sidewall 38 andlie directly over the bottom piece 36. The top piece 40 may have aninlet opening 60 therethrough. The inlet opening 60 may be at an inletheight 62 above the upper surface 46 of the bottom piece 36, which maybe greater than the outlet height 52. The inlet opening 60 may have adiameter 64 of, for example, between 0.10 and 0.30 inch. The inletheight 62 may be greater than the outlet height 52.

The channel 42 may be a passageway within the dispense head 30 thatinterconnects the inlet opening 60, the outlet openings 50, and thedrain opening 56.

Although not illustrated in detail in the previous figures, thedeveloper module 14 may further include an inlet valve 66, an outletvalve 68, and a pump 70. The pump 70 may have a low pressure side and ahigh pressure side. The inlet valve 66 may be connected to the inletopening 60 through a supply line 71. The outlet valve 68 may beconnected to the drain opening 56 through a drain line 73 on one sidethereof and the low pressure side of the pump 70 on the other sidethereof.

In use, as illustrated in FIGS. 2 and 4 a, a semiconductor substrate,such as a wafer 72, which may have a diameter, for example, of 200 or300 mm, may be placed on the wafer chuck 20 of the developer module 14.The computer controller 16 may control the rotational actuator 32 andthe vertical actuator 34 to move the dispense arm 24.

The vertical actuator 34 may lift the dispense arm 24 to a heightsufficient for the dispense head 30 to clear an upper edge of the catchcup 22. The rotational actuator 32 may then rotate the dispense arm 24so that the dispense head 30 is suspended above the semiconductor wafer72 as illustrated in FIG. 4 a.

As shown in FIG. 4 a, a liquid 74, such as a photoresist developersolvent, deionized water, or other such semiconductor processing liquid,may be supplied to the inlet valve 66. In the “normal” state, the inletvalve 66 is closed and the outlet valve 68 is open. Since the lowpressure side of the pump is connected to the channel 42 and the outletvalve 68 is open, a negative air pressure exits within the channel 42.The computer controller 16 may then control the valves 66 and 68 todeposit the liquid 74 onto the semiconductor wafer 72. As illustrated inFIG. 4 b, the computer controller 16 may open the inlet valve 66 and atthe same time, close the outlet valve 68, allowing the liquid 74 to flowdown the supply line 71.

As illustrated in FIG. 4 c, the liquid 74 may flow through the inletvalve 66, the supply line 71, and the inlet opening 60 and into thechannel 42 of the dispense head 30. The liquid 74 may then begin to fillthe channel 42.

Referring to FIG. 4 d, some of the liquid 74 may pass through the drainopening 56 and into the drain line 73, however, because the outlet valve68 is closed, none of the liquid 74 is able to pass through the outletvalve 68. Therefore, a depth 76 of the liquid continues to rise withinthe channel 42 of the dispense head 30. When the depth 76 of the liquid74 is greater than the outlet height 52, the liquid 74 flows downwardthrough the outlet openings 50, through the nozzles 44, and onto thesemiconductor wafer 72.

Referring to FIG. 4 e, when an appropriate amount of liquid 74, such as60 cubic centimeters, is deposited onto the semiconductor wafer 72, thecomputer controller 16 may restore the valves 66 and 68 to the normalstate. The inlet valve 66 may close so that no more liquid may passtherethrough, and the outlet valve 68 may open. Since the channel 42 ofthe dispense head 30 is now connected to the low pressure side of thepump, the remaining liquid 74 in the channel 42 may be sucked from thechannel 42 through the drain opening 56, the drain line 73, the outletvalve 68, and the pump 70. Once the depth 76 is below the outlet height52, all liquid 74 remaining in the channel 42 exits the channel 42through the drain opening 56. Although not illustrated, it should beunderstood that the liquid 74 may then be either disposed of or recycledto be used on a subsequent semiconductor wafer.

As illustrated in FIG. 4 f, the vacuum effect of the pump 70 removes anysolvent 74 remaining in the channel when the valves 66 and 68 are in thenormal state.

One advantage is that because of the vacuum effect of the pump 70 whenthe valves are in the normal state, any solvents remaining in thechannel is evacuated from the channel 42 through the drain opening 56and not the nozzles 44. Therefore, no unwanted solvent is accidentallyleaked or dripped onto the semiconductor wafer or another portion of thedeveloper module. Another advantage is that because of the use of thepump 70 on an opposing side of the dispense head 30 there is no need fora suck-back valve.

Other embodiments may not use the pump to draw the remaining liquid fromthe channel but rely on the force of gravity and capillary action todrain the remaining liquid. Embodiments utilizing the pump may not havean outlet height that is less than the inlet height and greater than thedrain height. Even though the dispense head as illustrated has onlyhaving one channel therethough, it should be noted that the dispensehead may have multiple channels with separate inlets, outlets, anddrains so that different types of solvents may be simultaneouslydispensed from a single dispense head without the solvents mixing withinthe dispense head.

While certain exemplary embodiments have been described and shown in theaccompanying drawings, it is to be understood that such embodiments aremerely illustrative and not restrictive of the current invention, andthat this invention is not restricted to the specific constructions andarrangements shown and described since modifications may occur to thoseordinarily skilled in the art.

1. A method comprising: connecting an opened first valve to a firstopening on a dispense head; connecting a closed second valve to a secondopening on the dispense head, a fluid flowing into a passageway of thedispense head through the first opening and out of the dispense headthrough a third opening; and closing the first valve and opening thesecond valve to drain the fluid from the dispense head through thesecond opening, wherein the passageway has a bottom, the first openingis at a first height above the bottom of the passageway, the thirdopening is at a second height above the bottom of the passageway, thesecond height being less than the first height, and the second openingis at a third height above the bottom of the passageway, the thirdheight being less than the second height.
 2. The method of claim 1,further comprising connecting a low pressure side of a pump to thesecond valve, the fluid flowing from the dispense head through thesecond valve and into the pump when the first valve is closed and thesecond valve is open.